The present invention relates generally to communication systems and, more particularly to packet-based communication systems. In particular, the present invention relates to a wireless communication system that incorporates Multicast IP addressing.
While the specification concludes with claims defining the features of the invention that are regarded as novel, it is believed that the invention will be better understood from a consideration of the following description in conjunction with the drawing figures, in which like reference numerals are carried forward.
Today""s wireless communication systems provide a broad range of services to individual subscriber units and groups of subscriber units, while either stationary or on the move. These services include, but are not limited to, cellular telephony, group dispatch, and packet data communication, to name a few. An example of such a system 100 is illustrated in FIG. 1. The configuration shown in FIG. 1 is typical in several standardized wireless communications systems, such as, for example Global System for Mobile Communication (GSM), Advanced Mobile Phone Service (AMPS), and Trans-European Trunked Radio (TETRA) systems. It may likewise be applicable to various proprietary communication systems such as, for example, the Integrated Digital Enhanced Network (iDEN(trademark)) or SMARTZONE(trademark) systems, which have, in the past, been available by contacting Motorola, Inc. at 1301 East Algonquin Road Schaumburg, Ill. 60196.
With reference to FIG. 1, a central switch 101 provides connections between sites 104-107. A plurality of subscriber units 110-115 wirelessly communicate with the sites 104-107 and each other, and are often logically divided into various subgroups or talk groups. In such a system, the call processing management and switching functionality are generally contained within the same physical unit, i.e., the central switch 101. The sites 104-107 are connected to the central switch 101 through dedicated or on-demand links and intermediate processors 102-103 in what is often called a xe2x80x9cstarxe2x80x9d configuration. Some very large systems use a hierarchy of such xe2x80x9cstarsxe2x80x9d where intervening concentrators group links from multiple sites and perform various lower level processing tasks before submission to the central switch.
Wireless communication networks as described above typically use a centralized mobility management function. As subscriber units move from site to site, they indicate movement to the network through handover and location update procedures. The location change information is forwarded to a hierarchical network of location databases, usually called visitor location registers (VLR) and home location registers (HLR). The centralized connection/mobility management functionality in the central switch 101 or hub, as it is frequently referred to, uses location information to determine which sites need to be included when a call request is made. While this star configuration and operations management meets the needs of the communication system previously mentioned, centralized and/or hierarchical communication system topologies nevertheless suffer from a number of problems.
First, the physical link back-haul required to support all links to the central switch or hub 101 can be quite cost prohibitive. In a typical system, all communications traffic is routed back to the central switch or hub 101. This may prove particularly expensive when either the switch 101 is located far from the site in question or in the case where the lines to the switch 101 are leased. Furthermore, the resulting network typically needs to be configured at the start of each call. That is, each time a call request is made, a series of dedicated network connections must be established before the call can proceed. This requirement frequently adds to otherwise undesirable processing delays.
Current systems also suffer from the risk of a single point of failure. That is, to say, if a central switch 101 goes down or is cut off from the network, large amounts of communications traffic will be lost and new call requests cannot be honored. Similarly, if the VLR associated with the central switch is somehow cut off from the network or fails, or if the HLR cannot be reached, calls to and from subscriber units are negatively impacted, and in many instances cannot be completed.
In accordance with the foregoing, there exists a need for a non-hierarchical communication system topology that decentralizes mobility processing. Such a system should provide easy scalability, minimize or eliminate network connection processing at call initiation, and avoid traditional susceptibilities to the single point of failure concern. In addition, such a system should be optimized to support a growing number user services such as, for example, telephone interconnect, group dispatch, messaging services (e.g., two-way alphanumeric paging), packet data transmission, voice and/or video communications, and combinations thereof (hereinafter referred to as xe2x80x9cMultimediaxe2x80x9d).